III. Select issues

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AIDS - the price of an epidemic

Until recently, policy-makers have viewed the human immunodeficiency virus (HIV), the cause of acquired immune deficiency syndrome (AIDS), as a health problem but, as the pandemic progresses, it appears that its effects are reverberating through all sectors of the economy, creating soaring health and social welfare costs, labour shortages and lowered productivity. The impacts on national economies, the agricultural sector and food security will be significant. Although available data are limited, they provide sufficient evidence that the profound demographic effects of AIDS will seriously hamper, if not reverse, economic growth in certain regions. There are at least three compelling reasons for urgent policy discussions of the effects of AIDS on developing country economies.

First, unlike most epidemics, AIDS is primarily transmitted by sexual contact; the sexually active sector of society is also the most economically productive - roughly 15 to 45 years of age. The survivors, children and the elderly, are least able to create a livelihood for themselves.

Second, although at present AIDS accounts for far fewer deaths than malaria, tuberculosis, heart disease or cancer, its rate of transmission is rapid. This is exacerbated by the fact that sexual behaviour is a private, even taboo, subject in many societies, which limits possibilities of intervention to arrest the spread of the disease. Infection rates are estimated to be doubling in as little as six months in some countries.

Finally, although AIDS is always fatal, in developing countries it can take as long as two years before infection results in death. This delay between cause and effect, the so-called "silent phase", does not encourage people to give up high-risk behaviour such as unsafe sex or intravenous drug use. It also means that the infected population can multiply rapidly before any symptoms appear to warn of its presence.

The World Health Organization (WHO) estimates that 14 million to 15 million people have been infected with HIV worldwide and that, during the next five years, this figure will rise to 40 million to 50 million, including millions of children; 90 percent of these cases will be in developing countries.

The economic impacts of AIDS

The unchecked spread of AIDS has the potential to create shortages among skilled and unskilled workers. Lengthy and recurrent bouts of illness seriously hamper workers' productivity; deaths rob children and elderly family members of their only means of support. Although skilled workers represent a smaller proportion of the population in developing countries, the cost of replacing their contributions presents a heavy burden.

Health care costs for treating AIDS patients, already very high, are expected to spiral. In several African cities, more than 50 percent of hospital beds are now occupied by AIDS patients. In the United Republic of Tanzania, clinicians estimate that, on average, HIV-infected adults suffer 17 episodes of HIV-related illness prior to death while children suffer from six to seven. The average health care costs per death from AIDS in developing countries is about 150 percent of per caput income. The excessive demand for health care created by HIV jeopardizes a nation's ability to deal with other pressing health problems and diverts resources from productive investments in other sectors.

Far more alarming are the indirect costs of AIDS - including loss of earnings of those affected - estimated to be at least ten times the direct health care costs. To give an idea of the magnitude, Thailand has estimated that the direct health care costs alone will run in the neighbourhood of $65 million by the year 2000. A UNDP study states that, in Asia, these costs will be borne primarily by individuals and their families (unlike Western economies where costs are usually covered by state or private insurance). This is likely to be the pattern in other developing regions, since public health care resources will be rapidly exhausted.

Scarce resources force governments to choose between investment in long-term growth and urgent short-term demands for health care. in developing countries, state-supported palliative care for AIDS victims is a relatively high short-term cost which provides no long-term benefit for society, since the disease is always fatal. in Kenya, for example, a 60-day hospital stay costs $938, three times the per caput GNP.

In the developing world, particularly in countries where agriculture constitutes a significant portion of the GDP, a reduced agricultural labour force as a result of AIDS deaths requires substantial capital investment to counteract declines in agricultural production.

Decreased food production endangers household and national food security. In six out of ten countries in sub-Saharan Africa, nutritional intake is already below minimum standards; a lowered nutritional status increases vulnerability to illness and death while leading to further declines in productivity. Furthermore, an unmet food demand increases dependency on imports and food aid.

The effects of AIDS on agricultural production have already been observed in Uganda, Tanzania and Zambia, where detailed surveys reveal that farmers cope with reduced labour by adopting practices that jeopardize immediate and future productivity. For example, delays and the inadequate execution or cessation of routine farming operations such as tilling, weeding, planting and mulching lead to poorer harvests; they also perpetuate or enlarge the perils of crop pests and diseases, thus creating hazards for individual households and entire communities.

Furthermore, labour shortages force farmers to reduce the land area under cultivation; if the land reverts to bush, it is difficult to reclaim, and usufruct rights may be lost owing to a lack of continuous cultivation. Crops may be chosen for their low-labour input rather than their nutritional value or marketability. As more labour-intensive crops are dropped, the range of crops declines and crop failures take on more significance because there is less to fall back on. Crop substitution may also reduce or eliminate cash crops destined for export, thereby worsening foreign exchange earning potential.

In addition to labour shortages, deaths of productive farmers erode agricultural knowledge, built up over centuries, regarding local cultivars and specialized cultivation skills and techniques. As a result, genetic diversity of adapted local crop varieties, the backbone of subsistence farming, may decline and some traditional varieties may become extinct.

Maintaining productivity levels with a depleted agricultural labour force requires capital investment to increase the productivity of remaining farmers or to attract labour from other sectors. In some countries, the barriers to achieving this are substantial.

For example, in Uganda agriculture currently accounts for 70 percent of GDP, 95 percent of export earnings and 90 percent of all employment. it is estimated that 20 percent of the population over 15 years of age is HIV-positive. As the death toll mounts, each productive person becomes responsible for a higher number of dependants; there will be about one million orphaned children in the next five years. Coping with illness and death is a constant drain on individual and community resources, making it increasingly difficult to maintain, much less increase, productivity. Since other sectors account for only 10 percent of the labour force in Uganda, and given the grim circumstances, the prospects of attracting additional labour to agriculture appear to be rather dim.

Labour can be substituted by other inputs such as expanded mechanization, increased access to credit, agrochemicals, improved seeds and extension education. Losses in productivity could be balanced by international aid and government investment for modernizing production methods. Since resources are scarce and the effects of AIDS are expected to have dramatic geographic variations, accurate local assessments are essential before interventions are undertaken.

A note on statistics

Global AIDS statistics are based on scant research and are subject to rapid change as research reveals new information about the disease. For example, in 1993 the Center for Disease Control in the United States expanded the definition of AIDS to include three new indicator diseases (pulmonary tuberculosis, recurrent bacterial pneumonia an invasive cervical cancer). These new diagnostics more than doubled the number of AIDS cases merely by changing the definition. If this phenomenon is observed in a country with one of the most developed AIDS programmes in the world, the difficulty of accurate global numbers can be grasped.

Furthermore, a lack of testing and diagnostic facilities makes estimates unreliably low. Low recorded and estimated numbers of both AIDS- and HIV-positive persons in developing countries are due to various factors, including: insufficient funds for testing; low rates of diagnosis because few AIDS victims are seen by doctors; misdiagnoses through lack of training and the prevalence of other concomitant ailments such as tuberculosis; and a lack of funds for keeping accurate records.

Many national HIV/AIDS estimates are based on back-calculations from diagnosed AIDS cases. This is misleading because such cases include only those who have fallen ill or died; as many as ten times that number may be HIV-positive. This estimate rises to 100 times in South and Southeast Asia where the pandemic is thought to be in its early stages. Despite this weakness, patterns that are useful to planners and policy-makers are beginning to emerge.


Acquired immune deficiency syndrome (AIDS) is the name of the fatal clinical condition that results from infection with the human immunodeficiency virus (HIV), which progressively damages the body's ability to protect itself from disease organisms. Thus, many AIDS deaths result from pneumonia, tuberculosis or diarrhoea; death is not caused by HIV itself but by one or more of these infections.

HIV-1 and HIV-2 are two similar viruses, both of which gradually erode the body's immune system. HIV-1 is found throughout the world; it has higher infection rates, currently doubling in about 5.7 years. WHO estimates that, in five years from now (in the year 2000), 30 million to 40 million people will be infected with HIV-1, half of whom will be in sub-Saharan Africa. The incidence of mother-infant transmission is 10 to 30 percent and many infants develop symptoms after four months. HIV-2 is found primarily, although not exclusively, in West Africa and has a doubling rate of 31 years; it is rarely passed on from mother to infant.

High-risk behaviour describes sexual intercourse (either male/female or male/male) without using a condom, or the sharing of needles to inject drugs. High-risk groups comprise, in epidemiological terms, people whose behaviour places them repeatedly at high risk, for example intravenous drug users, prostitutes, those who have several sex partners without using condoms. High-risk situations comprise inadequate health resources, low levels of education, poverty, rapid urbanization, social upheaval and social and economic marginalization and high levels of preventable diseases.

Source: British Medical Journal, 1991.

Regional overviews

At the end of 1993, two-thirds of all HIV carriers worldwide were estimated to be in sub-Saharan Africa, a region which accounts for only 10 percent of the global population. About 50 percent of the total population in this region is in the "high-risk and economically productive age cohort of 15 to 45 years of age; the birth rate is the highest, with a 3.2 percent population growth in the last decade, and per caput production also the lowest in the world. A recent study estimates that the GDP growth rate in sub-Saharan Africa will be halved in the next five years through deaths from AIDS.

For example, in the largest study of its kind in sub-Saharan Africa, the mortality among inhabitants in 15 villages in the Masaka District of Southwestern Uganda, mainly subsistence farmers, was observed over two years. More than 80 percent of deaths in the 13- to 44-year-old group were due to HIV-1. The highest mortality occurred in males from 25 to 34 years old and in females from 13 to 34 years old. A substantial number of these deaths occurred less than six months after the first symptoms appeared. The prevalence of HIV-1 is lower in Masaka than it is in many urban centres in Africa.

Furthermore, in sub-Saharan Africa the more rapidly infective HIV-1 is more common than HIV-2 and has activated outbreaks of tuberculosis, now the leading cause of death in HIV-positive people. Unlike HIV, tuberculosis is easily transmitted through routine household and casual contact, thus endangering family members and entire communities.

These factors alone are sufficient to set the scene for disaster. When other characteristics about the region are added - low crop yields and declining per caput production - it is clear that sub-Saharan Africa may be the global epicentre of death from AIDS, both from the disease itself and from its effects on livelihoods.

In Latin America and the Caribbean, transmission patterns have changed markedly in the last decade; male/female intercourse now accounts for 75 percent of infections and the number of perinatally infected children has risen dramatically. Between 1.5 million and two million people are thought to be infected, primarily in urban centres. Large numbers of tourists and business travellers, along with migrant workers, further the spread of infection. Brazil has the fourth highest reported number of AIDS cases in the world, and the number quadrupled from 1990 to 1992. On average, health care for an AIDS patient is estimated to be more than 800 percent of the per caput GNP.

In Asia, HIV infection is spreading more rapidly than anywhere else in the world. In Thailand, for example, the number of HIV-infected people doubled in 1990, has more than doubled again since then, and is expected to reach up to four million within five years. In 1992, the government implemented education, awareness and comprehensive monitoring programmes aimed at reducing rates of infection.

In India, in late 1992 HIV was estimated to be present in between 600000 and three million people.

In the Near East and North Africa, little information is available on AIDS and numbers of reported cases are very low. In Lebanon there is some concern that foreign-donated blood used for transfusions during the 15-year civil war may have been a source of infection. Also, many Lebanese who went to Africa during the war are now returning, some with AIDS. Despite the low numbers, the health ministry has already launched a strong public information programme to promote the use of condoms against infection.

Patterns of transmission and risk factors

At present, there is a high correlation between poverty and the rapid growth of AIDS. Where poverty is endemic, greater proportions of the population are both at a higher risk of infection and less able to mitigate against its effects. Other poverty-related health risks, such as poor nutrition and a lack of medicine and health infrastructure, ensure that the disease proceeds more rapidly from its onset to death. In sub-Saharan Africa, for example, the time from infection to death averages between six months and two years, whereas in developed countries it is ten years.

Epidemiological research has also revealed that high mobility elevates the risk of HIV infection. For example, high levels of seasonal or permanent migration, a flourishing tourist industry or a developed transportation infrastructure can all facilitate the rapid spread of the virus.

Sexual intercourse accounts for between 75 and 85 percent of HIV transmission; this includes male/female intercourse (70 to 75 percent) and male/male intercourse (5 to 10 percent). Other means of transmission are injecting drugs (5 to 10 percent), mother to infant (5 to 10 percent) and medical use of contaminated blood or blood products (3 to 5 percent). However, the averages mask important differences both between and within regions and countries.

In the early 1980s, AIDS was primarily an urban phenomenon, a feature now associated with the early stages of the pandemic. As we approach the middle of the second decade of AIDS, infection rates are mounting in rural areas. In a somewhat parallel movement, national epidemics appear to start in the highest socioeconomic stratum and move downwards. Similarly, in the early 1980s AIDS primarily affected the wealthier classes and this pattern can still be observed in countries where prevalence of the disease is low. If the transmission rate remains stable, the absolute number of HIV-affected people will increase simply because there are more people who are poor and live in rural areas.

As the disease moves down the socio-economic scale, it strengthens the grip of poverty. Poor people have less access to health care and education. Illiterate people are more economically vulnerable and their vulnerability is compounded because information on AIDS prevention rarely reaches them. In any case, condoms are en unavailable and unaffordable for poor people.

Poverty induces people to migrate in search of employment; this social dislocation often leads to high-risk behaviour such as drug abuse or involvement in the sex industry, either as a supplier or purchaser. Returning migrant workers are frequently a source of HIV infection. Poverty also influences attitudes towards risk; immediate needs for food and shelter may propel individuals to work in the sex industry to support themselves and their families in rural areas. Even outside the commercial sex industry, trading sex for material gains is common if other options for livelihood are not available.

AIDS has profound differential effects on women and men. Women's lack of equity is a leading risk factor in the spread of AIDS. First, a potent combination of biological and social reasons means that women are 2.5 times more likely to be infected by men than the reverse. Second, all other risk factors are compounded for women. They are more likely to be illiterate; more likely to be saddled with the care of the sick and dying, in addition to carrying heavier paid and unpaid workloads in the home, in agriculture and in other sectors. Poverty among women tends to limit all of their choices, including when and with whom to have sexual relations. They are the least likely to have knowledge of, access to, the means to purchase or the power to enforce the use of condoms.

In Africa and pans of Asia and Latin America, women contribute the bulk of agricultural labour. The loss of their contributions through family illness - their own or others' - therefore creates a substantial drop in productivity. Also, in many African countries, women have few legal rights, particularly property rights. A wife whose husband dies of AIDS is likely to be stripped of assets by her husband's family and sent home where she and her children become a burden on her own relatives. Alternatively, she may be taken on as a wife by one of her husband's brothers in which case, if she is HIV-infected, she will proceed to infect him and his other wives and any subsequent children. WHO predicts a 50 percent increase in infant mortality in sub-Saharan Africa during this decade as a result of AIDS.

Furthermore, in many developing countries, a woman's value and status in society are directly linked to her fertility. Failure to produce children can lead to social disgrace and humiliation, if not divorce and displacement in the marriage. This situation promotes the spread of AIDS because societal prohibition of contraception deters condom use.


AIDS is more than a health problem. It has significant, long-term socio-economic implications on food security, agricultural productivity and national economies.

Current annual worldwide expenditure on prevention of the disease is about $1.5 billion. Less than $200 million of this is spent in developing countries, where some 85 percent of infections occur. A recent study for WHO's Global Programme on AIDS suggested that comprehensive prevention of AIDS and sexually transmitted diseases could cost up to $2.9 billion per year in developing countries - ten to 15 times current spending levels. However, the study estimates that 9.5 million adult HIV infections could be averted from now until the year 2000. Early intervention aimed at high-risk, high-transmission groups is the most cost-effective means of bringing the spread of the virus under control. Because of the high numbers of sexual contacts in these groups, each infection avoided prevents an estimated ten times as many infections in the general population.

Crucial elements of AIDS prevention include providing information on how to avoid infection, promoting condom use, treating other sexually transmitted diseases and reducing blood-borne transmission.

Strong political will is essential to the fight against AIDS. However, interventions offer little political benefit and may be highly controversial because they pertain to sexual behaviour.

WHO cautions that no single strategy will meet the needs of every country. Therefore, policy-makers should perhaps view the AIDS pandemic as a series of "subepidemics" in countries and regions which have different characteristics such as their percentage of HIV prevalence, rates of transmission and numbers of AIDS cases. For example, Uganda has high numbers of AIDS cases while Thailand has high rates of HIV infection but, as yet, few cases of AIDS; each country will require a different approach.

The impacts of AIDS underline the need for policy measures to alleviate poverty and increase equity, particularly for women, who suffer the greatest consequences of AIDS. Removing discrimination against women - in the labour market, in access to credit and education and in property law, for example - will increase female income. It is well documented that higher levels of income and education among women are directly linked to improved child and family health. It is clear that AIDS will create a lower standard of living for everyone, not just those afflicted by the disease.

Finally, the issue must be raised regarding the involvement of agricultural policy-makers in dealing with AIDS and its consequences. The problem transcends agriculture and has wide economic, social and demographic implications. Nevertheless, to the extent of its impact on food security, agricultural public services need to formulate and implement measures to complement those related to education and information, health care and prevention and social assistance. However, the effectiveness of such measures hinges crucially on adequate knowledge. Not only is the disease not yet well understood but also its dynamics - current and prospective effects on urban and rural areas are inadequately researched and documented.

Agricultural policy-makers require more information about the likely effects of the disease on food supply and demand, i.e. how the balance between net food buyers (chiefly urban populations) and net food sellers is likely to evolve; and the extent to which AIDS and related effects may affect levels and patterns of agricultural output. On the demand side, research is needed on changes in levels and patterns of food consumption in the light of population and per caput income reductions. Policy action will then have to address such specific problems as: i) compensating for the loss of 15- to 45-year-old able-bodied farm workers by introducing labour-saving technology and creating incentives for farming; ii) consolidating farm holdings so that they remain in operation after the death of farmers - land tenure rules should be adjusted to give maximum flexibility for renting, selling or other arrangements and, if buying land is a viable option, credit may be needed; iii) compensating for reduced domestic supplies through food imports or food aid.

A global greenhouse

Global warming refers to the process whereby increasing atmospheric concentrations of "greenhouse gases" (GHGs) contribute to warming of the earth. In brief, while gases such as carbon dioxide, methane and water vapour are transparent to the sun's short-wave rays, they trap the radiant long-wave energy and reflect it back to the earth's surface. Many scientists believe that higher concentrations of these gases will cause an increase in global average temperatures.

Carbon dioxide (CO2) which is generated by burning fossil fuels and biomass, accounts for about 50 percent of the "radiative forcing" attributable to humans. Other important GHGs are methane (CH4), produced by marshes, landfills, livestock and wetland crops such as rice; and nitrous oxide (N2O), produced by nitrification and denitrification processes in soils, nitrogen fertilizer application and land-use changes. Current agricultural practices and land-use changes account for about one-third of anticipated greenhouse effects.

Although there is debate about whether or not global warming has already begun, many scientists agree that a slow rise will take place in the future. The main impacts of rising concentrations of GHGs are: increases in average temperatures, especially night-time temperatures in temperate regions; local changes in rainfall-evaporation ratios and associated shifts in agro-ecological zones; and increases in sea level by up to 40 cm by the year 2100 (as a result of thermal expansion of the ocean and possibly the melting of polar ice). Over the past century, the earth's annual near-surface temperature has risen by 0.3 to 0.6C, while the global sea level has risen by about 12 cm. These changes have already had some effects on agriculture as well as on local climates and other conditions of interest to agriculture.

FAO considers that there is still too much conjecture about certain features of climate change and national-level impacts on agriculture to warrant specific investment responses by developing countries, given their heavy financial requirements to meet more immediate food and agricultural needs. On the other hand, there is a degree of scientific consensus that the greenhouse effect is real, that concentrations of GHGs have been rising at unprecedented rates in the past decades, that global warming will slowly occur and that such changes will affect crop, animal, forest and fisheries sectors. Moreover, certain agricultural policy measures that make sense in any scenario and can be justified in benefit-cost terms could help slow the negative impacts of climate change.

An important theme linking the effects of global warming on agriculture, forestry and fisheries is that the most significant impacts may be the hardest to predict. Further, the broad trends in worldwide averages mask crucial differences in the incidence of warming-related damages. These differences are made more acute because countries likely to suffer most from warming may be the least able to respond.

Global warming linkages to agriculture, forestry and fisheries

It is difficult to predict how agricultural productivity will be affected by the higher temperatures associated with global warming, as many of the expected changes will have both positive and negative effects on production. For example, higher temperatures are likely to increase yields in higher-latitude countries but decrease yields in countries closer to the equator - the worst affected would be developing countries. Another expected change, increased CO2 concentrations, may increase plant growth - but this is likely to benefit both crop plants and weeds, heightening the competition between them for water and nutrients. Other experiments have shown higher water-use efficiency by plants at increased CO2 levels - which may become very important for semi-arid areas.

Similarly, global warming will have mixed effects on livestock production. in some locations, higher temperatures may encourage poleward migration of animal pests, promote herd growth or reduce feed requirements. Equally likely is that livestock numbers will be reduced in other locations. The effects on fisheries would be similarly mixed. Complex interactions between surface warming, warm and cold ocean currents and interrelated marine species make it difficult to predict the impacts on populations of specific commercial fish species.

A possible sea level rise of several hundred millimetres would not only affect the coastline and the structures along it, but also the hydrology, soils and natural or cultivated vegetation over an appreciable distance inland. The nature and extent of these changes depends on the length of the dry season, the sediment supply from rivers and the incidence of storms and cyclones.

The natural ranges of many tree species could advance to higher latitudes or higher altitudes as temperatures increase. Forests stressed by climate change would become more susceptible to damage by fire, insects, pollution and disease. Genetic diversity could be reduced, leaving only the more resistant genotypes, and areas and many tree and undergrowth species could be lost.

Some researchers draw an important distinction between the effects of global warming on worldwide production and on consumption and producer gains. For instance, warming could lower yields in one region by 5 percent but increase world prices by 10 percent, thereby reducing the negative impact on agriculture. Therefore, the regional impacts are expected to differ greatly. As a result, the attractive locations for many agricultural activities may move, often across national or regulatory boundaries.

In the absence of large-scale field experiments, no clear-cut conclusions can be reached on the geographic distribution of the impacts, on the interaction between environmental and socioeconomic factors or on the agricultural sectors most likely to be affected. Indications, however, suggest that: i) in the absence of stress conditions, many annual crops could benefit from the CO2 fertilization effect and improved water-use efficiency; ii) natural vegetation and some perennial crops are less likely to benefit and may actually suffer to an extent that is largely unknown; iii) the quality of agricultural products and their nutritional value, soils, crop and forest interaction with pests and diseases, and water availability may be affected; iv) climate change impacts between developed and developing countries are likely to be uneven; v) interseasonal and interannual variabilities of climate are likely to increase, resulting in higher risks of crop failures and food shortages.

These indications are, however, largely uncertain owing to the lack of confidence in global circulation models and to the insufficient knowledge of the biophysical responses of crops and ecosystems to elevated levels of CO2.

Contribution to GHGs from agriculture, forestry and fisheries

The agricultural, forestry and fisheries activities that contribute to GHG emissions are relatively few. Deforestation is the most important source of CO2 emissions from agriculture and forestry. Livestock and irrigated and wetland crop production account for 70 percent of total CH4 emissions (see Table 2); emissions of N2O are mostly associated with changing soil management practices (which modify natural nitrification and denitrification processes), wood burning and, to a small extent, the use of nitrogen fertilizers.

The overall policy approach

Global warming is similar to ozone depletion in the stratosphere in that the emissions in one country have almost the same impact as those released in another. However, the emissions of ozonedepleting chemicals are concentrated in a relatively small number of countries and their production is dominated by relatively few firms. These factors make it easier to arrive at a series of agreements that progressively restrict the production and release of such chemicals.

By contrast, emissions of GHGs are spread throughout the world and are attributable to almost every firm and household. This feature requires wide-scale international coordination and complicates the task of monitoring and enforcing emerging policies.

The time lapse between cause and effect presents problems for a worldwide response to global warming. For example, while the local effects of some industrial emissions are dramatically reduced within days of cessation, the most significant effects of GHG emissions are expected to occur over the next century. Thus, given the scientific uncertainties about global warming and its effects, together with the expected costs of cutting emissions, agreements to reduce GHGs are difficult to achieve.

Given these complications and uncertainties, the emerging policy approach has two stages at the international level. in the first (short-term) stage, the focus would be on research and a "no-regrets" polity approach. The second (longer-term) stage would involve tough commitments to deal with warming which would follow only if further research shows that global warming must be avoided.

Short-term responses and no-regrets policies

A no-regrets response to global warming would include technological and economic policies that are justifiable even if global warming does not become a problem. These responses include using existing technologies that are economically feasible.

TABLE 2 - Agricultural greenhouse gases and trends

  CO2 CH4 N2O
Atmospheric lifetime 120 yrs 10.5 yrs 132 yrs
Global warming potential, direct1 1 11 70
Global warming potential, indirect2 0 10 ...
Pre-industrial levels (1750-1800) 280 ppmv 0.80 ppmv 288 ppbv
Present-day levels (1990) 353 ppmv 1.72 ppmv 310 ppbv
Average yearly increase (%) 0.53 0.94 0.25
Reduction in emissions required for stabilization at current levels (%) > 60 15-20 70-80
Emissions from agriculture (%) 30 70 90
Main agricultural sources Deforestation Irrigated and wetland crops; ruminant digestion Soil management practices; nitrogen fertilizer use
Trend 1900/1990-2100 Decreasing 10-30% increase 5-10% increase

1 In relation to CO2 at a 100-year time horizon.
2 Through chemical transformation.
3 Increase much less than linear since 1990.
4 Increase less than linear since 1980; at present nearly stable.
Note: Concentration specified as: ppmv = parts per 106 by volume; ppbv = parts per 109 by volume.
Sources: IPCC Second Assessment Report 1992; and R. Brinkman and W.G. Sombroek. The effects of global climatic change on soil conditions in relation to plant growth and food production. In D. Norse and W.G. Sombroek, eds. Global climatic change and agricultural production. Direct and indirect effects of changing hydrological, soil and plant physological processes. Chichester, UK, Wiley. (in press).

For example, existing and affordable energy-efficient lighting technologies would reduce fossil fuel consumption. Greater use of such technologies would require public education. Similarly, current techniques that make more efficient use of nitrogen fertilizers are already justified by decreased costs and increased productivity, but they will also reduce emissions of N2O.

The no-regrets approach involves policy changes that are already justifiable and desirable for improving economic efficiency but that would also have important direct or indirect impacts on GHG emissions - such policy changes include addressing market systems and policies that distort economic costs and underprice resources - such policy reforms generally have the characteristics of no-regrets actions in that they are desirable, even without global warming.

Policy linkages to agriculture, forestry and fisheries

Some important agricultural policies that may be encouraged because they contribute to GHG abatement include reforestation, soil organic matter conservation and improved efficiency of irrigation systems and fertilizer application. Many argue that actions to reduce deforestation in some developing countries should be described as no-regrets responses, partly since many other serious problems are associated with deforestation (loss of biodiversity and diminished watershed protection). CO2 abatement also includes improving energy efficiency and reducing or eliminating fuel subsidies for agricultural users. Measures to improve fertilizer formulations and to decrease fertilizer waste could reduce N2O emissions; measures that improve the quality of livestock feeds may reduce CH4 and N2O emissions. If global warming is deemed to be a serious enough threat, taxes on fertilizer use or restrictions on energy inputs may have to be considered. The latter policy options will not be viable in many developing countries with actual or impending food shortages. Ongoing research may identify other ways of reducing the emissions concerned.

Although CH4 is an important component of agriculture's contribution to global warming, there is currently little discussion of using taxes or quantity restrictions to reduce these emissions. Alternatives to taxes or quotas could include different cropping practices (in the case of rice, for example), or the production and provision of higher-quality feeds (in the case of livestock). in the longer term, however, if warming becomes an acute problem, more binding policies (such as taxes on goods with high CH4 emissions or quotas on these outputs) may have to be considered. In addition, there is a need for expanded research and education about other techniques for reducing CH4 emissions, such as better management of landfills and livestock wastes.

In the case of forestry, two longer-term responses are being discussed. First, further attention should be paid to counteracting deforestation. Governments should be encouraged to eliminate policies that contribute to deforestation and to promote reforestation in some cases. The real returns to agriculture from forest clearing in many parts of the world are very low, and reducing deforestation may be an efficient way of reducing current levels of CO2 emissions by up to 10 percent. International loans may provide gap funding for those countries seeking to stop unwanted deforestation.

Second, reforestation involving planting trees on previously cropped land or the expansion of existing forests would sequester additional carbon. However, recent research questions its cost-effectiveness on a large scale. These studies argue that there is a limited supply of land suitable for growing trees as an economically viable alternative. In the simplest terms, the land that tends to be best for "carbon forestry" also tends to be reasonably good for crops, thus increasing the opportunity cost of the land. Further, reforestation absorbs carbon only as long as the forest is growing, since once it achieves maturity, carbon losses through decomposition and fires offset the carbon taken up by new growth. In contrast, the extra storage of carbon in soil organic matter, already two to three times that of standing biomass, offers more possibilities while also improving soil quality.

Research into the effects of warming, reducing emissions and mitigating the consequences is likely to be expanded in a number of directions. Among the many areas of great interest to agriculture, forestry and fisheries is that of research into the effects of changes in water levels on wetland crops and the local changes in rainfall-evaporation ratios, including the consequences for local plant growth and water for downstream irrigation. More generally, ongoing research may reduce uncertainties for policy formulation. However, lack of research should not be an excuse for inaction in crucial areas, particularly where projects or policies under consideration have no-regrets justifications.

Longer-term responses

If global warming is "confirmed", policy-makers must consider another set of longer-term policy options. The most important of these would aim to curtail the burning of fossil fuels. Supplementary policy responses would be directed at agriculture and forestry, as indicated above.

CO2 emissions can be reduced by: increasing energy efficiency; reducing energy use; changing the mix of fossil fuel use; and substituting biomass for fossil fuels. For example, policies that shift the demand for energy away from high carbon-content fuels such as coal to lower carbon-content fuels such as natural gas will reduce CO2 emissions because they generate less CO2 per unit of energy. Even more significant reductions would follow from substituting carbon-free energy such as hydroelectricity, geothermal, solar and wind energy or bio-energy.


One of the major challenges to policy-makers in the coming decades is the broad range of uncertainty surrounding global warming, its likely climatic and biological effects and its effects on specific sectors of the economy as well as on society at large. These uncertainties are particularly pronounced for agriculture, and they grow greater the further one looks into the future. Finally, the greatest uncertainty concerns the level of geographic detail necessary for appropriate policy-making. As a result of this uncertainty, there is a pressing need for information on relevant linkages.

Crucial international equity issues must also be addressed in order to evaluate who will bear the cost of greenhouse warming abatement. For the purposes of agricultural policy-making, the issues raised above may help determine which approaches to the abatement of greenhouse warming will be affordable for high- and low-income countries, respectively.

Uruguay Round of multilateral trade negotiations

The Uruguay Round of GATT multilateral trade negotiations (MTNs) was launched in 1986 at Punta del Este, Uruguay. The Final Act concluding the Round was signed at Marrakesh in April 1994. It includes agreements and decisions that will be of economic significance to the world and to the developing countries. Of greatest direct concern to the agricultural sector are the Agreement on Agriculture, the Agreement on the Application of Sanitary and Phytosanitary Measures and the Decision on Measures Concerning the Possible Negative Effects of the Reform Programme on Least-Developed and Net Food-Importing Developing Countries.

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